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2" to 1.25" adapter on barlow


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I am getting into visual observing and am planning an eyepiece kit for my soon to arrive dobsonian. My question is, is there a distance the eyepiece needs to be from the glass of a barlow? I am wondering if I get a 2" barlow and want to use a 1.25" eyepiece in it, will using the required 2" to 1.25" adapter for the eyepiece, space the eyepiece too far back for it to function properly or will there be negative affects like vignetting, aberrations or inability to focus?

Any help would be appreciated. 

Thank you.

 

 

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If it is a barlow then the distance will affect the magnification factor. With a telextender this is not the case. However, a 2" barlow and 2" eyepieces are very heavy items. Unless you only have very wide angle eyepieces, e.g. 100°, where the whole set is in the 2" format, I would not consider a 2" barlow for a second. You will be better off getting mid range eyepieces (in terms of magnification) in a 1.25" fitting and then a 1.25" barlow for some or all of your high powers. 

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The GSO/Revelation 2x ED 2" Barlow comes with a 2" to 1.25" adapter that recesses into the 2" tube via a notch on the side.  It then has a recession in it to allow most 1.25" eyepieces to be roughly flush with the top of the 2" tube so they will remain parfocal with 2" eyepieces.

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Excellent, thank you guys very much for your response. Weight will probably be something for me to keep in mind and something I didn't think about although that barlow above intrigues me. 

Thanks again, much appreciated. 

 

 

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